In recent years, wind turbines have increased in popularity as a means of electrical power generation. Wind turbines offer the advantages of relatively inexpensively generating power from a renewable energy source as well as having a low impact on the surrounding environment.
Rotating components in machinery such as wind turbines are typically supported by bearings so as to minimize the amount of friction between the rotating and non-rotating components of the machinery in question. To minimize component wear and further reduce friction, the bearing assemblies are lubricated by oils, greases or similar substances. Retention of the lubricants within the bearing assembly is vital, as lubricant leakage out of the bearing assembly can lead to increased friction, component failure, as well as contamination of the surrounding environment. Likewise, it is necessary to impede the entry of external contaminants into the bearing assembly to protect components and maintain low friction.
As the bearing assemblies contain both static and rotating components, forming an effective, low-friction seal between the interior and exterior of the assembly presents difficulties. Sealing solutions include contact and non-contact seal arrangements; however, each type of seal has its shortcomings. Contacting seals wear out and weaken due to friction between the static and rotating parts, eventually resulting in lubricant leakage and contaminant entry. Non-contacting seals can reduce lubricant leakage while maintaining low friction and eliminating wear on the seal components; however, such seals do not completely eliminate leakage, especially in applications with large component diameters, and may not completely prevent contaminant entry. An effective, low friction seal arrangement for large diameter applications is therefore desired.